Neutrale aromatische Tetraepoxyannulene: Tetraepoxy[26]annulene(4.2.2.2) und Tetraepoxy[30]annulene(4.4.4.2) – Systeme mit hoher molekularer Dynamik

Neutral Aromatic Tetraepoxyannulenes: Tetraepoxy[26]annulenes(4.2.2.2) and Tetraepoxy[30]annulenes(4.4.4.2) – Systems with High Molecular Dynamics The twofold cyclizing Wittig reaction of the bis‐aldehyde 6 with the ylide of the bis‐phosphonium salt 7 yields tetraepoxy[26]annulene(4.2.2.2) 4 , which exists in the two isomeric forms 4a (EE,Z,E,Z) and 4b (EE,Z,E,E). Annulene 4a is a highly dynamic system down to −80°. Temperature‐dependent ¹H‐NMR spectra of 4a establish that the (E,E)‐buta‐1,3‐dien‐1,4‐diyl as well as the (E)‐ethen‐1,2‐diyl bridges rotate around the adjacent σ‐bonds in a synchronous manner. Isomer 4b , for steric reasons, is rigid. By Wittig reaction of the bis‐aldehyde 8 with the ylide of the bis‐phosphonium salt 9 , the tetraepoxy[30]annulene(4.4.4.2) 5 is obtained, which exists also in two isomeric forms, 5a and 5b . Only 5a (EE,ZE,EE,Z) can be isolated in pure form. Like 4a , 5a is highly dynamic, the (E,E)‐buta‐1,3‐dien‐1,4‐diyl as well as the opposite (E)‐ethen‐1,2‐diyl bridge being able to rotate down to −80°. The ¹H‐NMR spectrum at −80° indicates that 5a exists in the stable conformation 5a′ . The 26‐ and 30‐membered annulenes belong to the most expanded neutral annulenes known hitherto; their ¹H‐NMR spectra confirm that they still have diatropic, aromatic character.     

Diepoxy[18]annulene(10.0) : (Z,E,Z,E,Z)‐Diepoxy[18]annulen(10.0) – ein hochdynamisches Annulen

Diepoxy[18]annulenes(10.0): ( Z , E , Z , E , Z )‐Diepoxy[18]annulene(10.0) – a Highly Dynamic Annulene The McMurry reaction of (all‐E)‐5,5′‐([2,2′‐bifuran]‐5,5′‐diyl)bis[penta‐2,4‐dienal] ( 13 ) only occurs intramolecularly to give a mixture of the diepoxy[18]annulenes(10.0) 6 and 7 . Tetraepoxy[36]annulene(10.0.10.0) resulting from an intermolecular McMurry reaction is not formed. According to spectroscopic data, 6 is (Z,E,Z,E,Z)‐ and 7 (Z,E,E,Z,E)‐configured. The ¹H‐NMR data confirm that in 6 the (E)‐ethene‐1,2‐diyl bonds (C(11)=C(12) and C(15)=C(16)) rotate around the adjacent σ‐bonds. Beginning at −70°, this rotation freezes, and 6 is becoming a diatropic aromatic ring system. Beside [18]annulene itself, (Z,E,Z,E,Z)‐diepoxy[18]annulene(10.0) 6 is the only hitherto known [18]annulene derivative with dynamic properties.     

Konfigurations- und konformationsisomere paratrope,rotationsdynamische Tetraepoxy[32]annulene(6.2.6.2) und diatrope Tetraoxa[30]porphyrin(6.2.6.2)-Dikationen : Nachweis eines Tetraepoxy[31]annulen(6.2.6.2)-Radikalkations

Configurational and Conformational Isomeric Paratopic, Rotational Dynamics Tetraepoxy[30]annulenes(6.2.6.2) and Diatropic Tetraoxa[30]porphyrin(6.2.6.2) Dications: Detection of a Tetraepoxy[31]annulene(6.2.6.2)Radical Cation The synthesis of tetraepoxy[32]annulenes(6.2.6.2) ( 4 ) by a cyclizing twofold Wittig reaction of (E,E,E)-5,5′-(hexa-1,3,5-triene-1,6-diyl)bis[furan-2-carbaldehyde] ( 6 ) and the corresponding bis-phosphonium salt 7 is described (Scheme 1). Contrary to the configuration of the educts, the obtained annulenes 4a and 4b are (Z,E,E,E,Z,E,E,E)- and (E,Z,E,E,E,Z,E,E)-configurated, respectively. The ¹H-NMR spectra establish the paratropic, antiaromatic character of 4 . The annulenes 4 are highly dynamic systems, the (E)-ethenediyl bridges rotate around the adjacent σ-bonds, these rotations are frozen at −80°. The McMurry condensation of dialdehyde 6 yields the (E,E,Z,E,E,E,Z)-4,5-dihydrotetraepoxy[32]annulene(6.2.6.2) ( 13a ), where the configuration of the dialdehyde 6 – beside the hydrogenated double bond – is retained. As result of an intramolecular McMurry reaction of 6 , (Z,E,Z,Z)-dioxa[16]annulene(6.2) 14 is formed. By oxidation of the [32]annulenes(6.2.6.2) 4a and 4b , a mixture of the four stereoisomeric tetraoxa[30]porphyrin(6.2.6.2) dications 5a / 5a ′/ 5b / 5c is obtained; the configuration of the isomers is determined by COSY, NOESY, and NOE experiments. The Δδ values (26.81, 25.83, and 21.11 ppm) underline the diatropic, aromatic character of the dications 5 , the Soret bands are shifted bathochromically to 550 nm, and the Q-bands are in the NIR region (896 – 1039 nm). The dihydroannulene 13a is dehydrogenated by p-chloroanil (tetrachloro-1,4-benzoquinone) to give the annulenes 4a and 4b , its oxidation with DDQ (=4,5-dichloro-3,6-dioxocyclohexa-1,4-diene-1,2-dicarbonitrile) results in the same mixture of dications 5 . Entirely different results are obtained by reaction of the dihydroannulene 13a with DDQ. Here, the (E,E,E,Z,E,E,E,Z) tetraoxa[30]porphyrin(6.2.6.2) dication 5c – formed only in traces from 4a / 4b – is the main product. Beside 5c , a by-product (3%) can be isolated, which turns out (ESR, conductivity) to be the (E,E,E,Z,E,E,E,Z)-tetraoxa[31]porphyrin(6.2.6.2) radical cation 16 , obviously the intermediate in the oxidation sequence of the annulene to the dication. This result leads to the conclusion that the reaction of the dihydro compound 13a with p-chloroanil and DDQ follows different reaction mechanisms. For all isolated stereoisomeric tetraepoxy annulenes and tetraoxaporphyrin dications, the ΔH_f values are calculated by the semiempiric AM1 method. The results are in agreement with the experimental observations. All data confirm the antiaromaticity of the tetraepoxy[32]annulenes(6.2.6.2) 4 and the aromaticity of the tetraoxa[30]porphyrin(6.2.6.2) dications.     

Annulenoide Tetrathiafulvalene:, 5,16‐Bis(1,3‐benzodithiol‐2‐yliden)‐5,16‐dihydrotetraepoxy‐ und 5,16‐Bis(1,3‐benzodithiol‐2‐yliden)‐5,16‐dihydrotetraepithio[22]annulene(2.1.2.1)

Annulenoid Tetrathiafulvalenes: 5,16‐Bis(1,3‐benzodithiol‐2‐ylidene)‐5,16‐dihydrotetraepoxy‐ and 5,16‐Bis(1,3‐benzodithiol‐2‐ylidene)‐5,16‐dihydrotetraepithio[22]annulenes(2.1.2.1) The title compounds are among the first tetrathiafulvalenes with annulene spacers, here with tetraepoxy‐[22]annulene(2.1.2.1) (see 3a ), tetraepithio[22]annulene(2.1.2.1) (see 3b ), and diepithiodiepoxy[22]annulene(2.1.2.1) (see 23 ) units. The annulenoid tetrathiafulvalenes 3a and 3b are prepared by cyclizing McMurry coupling of the 5,5′‐(1,3‐benzodithiol‐2‐ylidenemethylene)bis[furan‐ or thiophene‐2‐carbaldehydes] ( 8a or 8b , resp.) or by Wittig reaction of (1,3‐benzodithiol‐2‐yl)tributylphosphonium tetrafluoroborate ( 13b ) with tetraepoxy[22]annulene(2.1.2.1)‐1,12‐dione 20 (formation of 3a ) or diepithiodiepoxy[22]annulene(2.1.2.1)‐1,12‐dione 22 (formation of 23 ). The annulenoide tetrathiafulvalene 3a is obtained as a mixture of the isomers (E,E)‐ and (Z,Z)‐ 3a . At 130°, (Z,Z)‐ 3a rearranges quantitatively into the (E,E)‐isomer. Isomer (E,E)‐ 3a is a dynamic molecule, where the (E)‐ethene‐1,2‐diyl bridges rotate around the adjacent σ‐bonds. The tetraepithioannulene derivative 3b as well as 23 only exist in the (Z,Z)‐configuration. The oxidation of (E,E/Z,Z)‐ 3a with Br₂ yields the annulene‐bridged tetrathiafulvalene dication (E,E)‐ 3a _Ox, while with 4,5‐dichloro‐3,6‐dioxocyclohexa‐1,4‐diene‐1,2‐dicarbonitrile (DDQ) obviously only the radical cation 3a _Sem is formed, which belongs to the class of cyanine‐like violenes. The annulenoide tetrathiafulvalenes 3b and 23 , which exist only in the (Z,Z)‐configuration, obviously for steric reasons, cannot be oxidized by DDQ. Electrochemical studies are in agreement with these results.     

Tetraepoxy[32]annulene(4.4.4.4) und `Tetraoxa[30]porphyrin(4.4.4.4)'‐Dikationen

Tetraepoxy[32]annulenes(4.4.4.4) and `Tetraoxa[30]porphyrin(4.4.4.4)' Dications Of the tetraepoxy[32]annulenes as well as the `tetraoxa[30]porphyrin' dications, hithertoo only the (8.0.8.0) and the (6.2.6.2) systems are known to exist in several geometric isomers and to possess antiaromatic and aromatic character, respectively. Here we describe the still missing symmetric member of the [32]annulenes, the tetraepoxy[32]annulene(4.4.4.4) 1 and the corresponding `tetraoxa[30]porphyrin(4.4.4.4)' dication 2 . The cyclizing Wittig reaction of the dialdehyde 3 with the bis‐phosphonium salt 7 at 70° yields the configurational isomers 1a (ZE,EE,EZ,EE), 1b (ZE,EE,EE,EE), and 1c (EZ,EE,EZ,EE). All isomers are antiaromatic; in 1a and 1c , the two (E,E)‐buta‐1,3‐diene‐1,4‐diyl bridges rotate around the adjacent σ‐bonds; the rigidity of 1b with 3 (E,E) bridges prevents any dynamic character. The Wittig reaction of 3 with 7 at 20° only yields the kinetically controlled annulene 1c , and at 120°, an excess of the thermodynamically most stable isomer 1a is formed. The structure of 1 is elucidated mainly by COSY and NOESY experiments, and the dynamic character of 1a and 1c is established by temperature‐dependent <sup>1</sup>H‐NMR spectroscopy. The oxidation of the isomer mixture 1a – c with 4,5‐dichloro‐3,6‐dioxocyclohexa‐1,4‐diene‐1,2‐dicarbonitrile (DDQ) gives two isomeric `tetraoxa[30]porphyrin(4.4.4.4)' dications 2′ and 2″ , which are frozen conformers with the same (EZ,EE,EZ,EE)‐configuration and geometrically related to 1c . Semiempirical calculations of 1 and 2 are in full agreement with the experimental results.     

‘Oligomere' Kondensationsprodukte von (1E,3E,5E)‐1,6‐Di(2‐furyl)hexa‐1,3,5‐trien mit Acetaldehyd: Tetrahydro‐tetramethyl‐octaepoxy[60]annulen(6.1.6.1.6.1.6.1)

Oligomeric Condensation Products of (1 E ,3 E ,5 E )‐1,6‐Di(2‐furyl)hexa‐1,3,5‐triene with Acetaldehyde: Tetrahydro‐tetramethyl‐octaepoxy[60]annulene(6.1.6.1.6.1.6.1) The Ca(NO₃)₂‐induced condensation of (1E,3E,5E)‐1,6‐di(2‐furyl)hexa‐1,3,5‐triene ( 6 ) with acetaldehyde yields the linear ‘oligomers' 7 – 11 with 2–6 1,6‐di(2‐furyl)hexa‐1,3,5‐triene units and 1–4 acetaldehyde units, besides a cyclic condensation product 12 obtained from 4 equiv. of 6 with 4 equiv. of acetaldehyde. According to spectroscopic studies, 12 is the tetrahydro‐tetramethyl‐octaepoxy[60]annulene(6.1.6.1.6.1.6.1) as the most expanded annulene system known so far. While the dehydrogenation of 12 to give the tetramethyl‐octaepoxy[60]annulene(6.1.6.1.6.1.6.1) cannot be achieved, the oxidation of 12 with Br₂ yields a black, in all organic solvents nearly insoluble solid 14 , which possibly is the tetramethyl‐octaepoxy[58]annulene(6.1.6.1.6.1.6.1) dication. Because of the insolubility of 14 , unfortunately most of its spectroscopic data are not available. However, the λ_max values in the UV/VIS/NIR spectrum of 14 (Soret and Q bands) are in line with the values of the tetraepoxy[26]annulene(4.2.4.2) dication, the tetraepoxy[30]annulene(4.4.4.4) dication, and the tetraepoxy[34]annulene(6.4.6.4) dication.     

8,19-Dimethyl-tetraepoxy[22]annulen(2.1.2.1): ein erstes Tetraepoxy-Verbrücktes aromatisches [22]Annulen

8,19-Dimethyl-tetraepoxy[22]annulen(2.1.2.1): The First Tetraepoxy-Bridged Aromatic[22]Annulene By McMurry reaction of 5,5′-ethylidenebis[furan-2-carbaldehyde] ( 15 ), a syn/anti mixture 16 of (E,E)- and (Z,Z)-8,19-dihydro-8,19-dimethyl-tetraepoxy[22]annulene is obtained. The (E/E)-isomers 16 are the first rotation- ally active noncyclic conjugated macrocycles, where the (E)-ethenediyl moieties rotate around the connecting single bonds. The dihydro-tetraepoxy[22]annulenes 16 are dehydrogenated by (Ph₃C)BF₄ as well as by O₂ to give the tetraepoxy[22]annulene 11 . The spectroscopic data support the character of 11 as an aromatic, diatropic ring system, which is rather sensitive towards O₂. In the oxidation mixture obtained from 11 , beside polymeric products, two compounds 19 and 20 can be isolated, carrying one and two CHO groups, respectively, resulting by oxidation of one or both Me-groups but having retained the aromatic 22π system of 11 .     

Quinolone Analogs 13: Synthesis of Novel 1,1′‐(2‐Methylenepropane‐1,3‐diyl)di(4‐quinolone‐3‐carboxylate) and Related Compounds

The reaction of the 4‐hydroxyquinoline‐3‐carboxylate 6 with pentaerythritol tribromide gave the 1,1′‐(2‐methylenepropane‐1,3‐diyl)di(4‐quinolone‐3‐carboxylate) 11 , whose reaction with bromine afforded the 1,1′‐(2‐bromo‐2‐bromomethylpropane‐1,3‐diyl)di(4‐quinolone‐3‐carboxylate) 12 . Compound 12 was transformed into the (Z)‐1,1′‐(2‐acetoxymethylpropene‐1,3‐diyl)di(4‐quinolone‐3‐carboxylate) 13 or (E)‐1,1′‐[2‐(imidazol‐1‐ylmethyl)propene‐1,3‐diyl]di(4‐quinolone‐3‐carboxylate) 14 . Hydrolysis of the dimer (Z)‐ 13 or (E)‐ 14 with potassium hydroxide provided the (E)‐1,1′‐(2‐hydroxymethylpropene‐1,3‐diyl)di(4‐quinolone‐3‐carboxylic acid) 15 or (Z)‐1,1′‐[2‐(imidazol‐1‐ylmethyl)propene‐1,3‐diyl]di(4‐quinolone‐3‐carboxylic acid) 16 , respectively. The nuclear Overhauser effect (NOE) spectral data supported that those hydrolysis resulted in the geometrical conversion of (Z)‐ 13 into (E)‐ 15 or (E)‐ 14 into (Z)‐ 16 .     

(E/Z)‐Isomerization of (all‐E)‐5,6‐Diepikarpoxanthin

(all‐E)‐5,6‐Diepikarpoxanthin (=(all‐E,3S,5S,6S,3′R)‐5,6‐dihydro‐β,β‐carotene‐3,5,6,3′‐tetrol; 1 ) was submitted to thermal isomerization and I₂‐catalyzed photoisomerization. The structures of the main products, i.e. (9Z)‐ ( 2 ), (9′Z)‐ ( 3 ), (13Z)‐ ( 4 ), (13′Z)‐ ( 5 ), and (15Z)‐5,6‐diepikarpoxanthin ( 6 ), were determined by their UV/VIS, CD, ¹H‐NMR, and mass spectra. In addition, (9Z,13′Z)‐ or (13Z,9′Z)‐ ( 7 ), (9Z,9′Z)‐ ( 8 ), and (9Z,13Z)‐ or (9′Z,13′Z)‐5,6‐diepikarpoxanthin ( 9 ) were tentatively identified as minor products of the I₂‐catalyzed photoisomerization.     

Synthesis and crystal structure of the dinuclear copper(II) Schiff base complex μ‐hydroxido‐μ‐chlorido‐bis{[bis(trans‐2‐nitrocinnamaldehyde)ethylenediamine]chloridocopper(II)} dichloromethane sesquisolvate

Transition metal complexes of Schiff base ligands have been shown to have particular application in catalysis and magnetism. The chemistry of copper complexes is of interest owing to their importance in biological and industrial processes. The reaction of copper(I) chloride with the bidentate Schiff base N,N′‐bis(trans‐2‐nitrocinnamaldehyde)ethylenediamine {Nca₂en, systematic name: (1E,1′E,2E,2′E)‐N,N′‐(ethane‐1,2‐diyl)bis[3‐(2‐nitrophenyl)prop‐2‐en‐1‐imine]} in a 1:1 molar ratio in dichloromethane without exclusion of air or moisture resulted in the formation of the title complex μ‐chlorido‐μ‐hydroxido‐bis(chlorido{(1E,1′E,2E,2′E)‐N,N′‐(ethane‐1,2‐diyl)bis[3‐(2‐nitrophenyl)prop‐2‐en‐1‐imine]‐κ²N,N′}copper(II)) dichloromethane sesquisolvate, [Cu₂Cl₃(OH)(C₂₀H₁₈N₄O₄)₂]·1.5CH₂Cl₂. The dinuclear complex has a folded four‐membered ring in an unsymmetrical Cu₂OCl₃ core in which the approximate trigonal bipyramidal coordination displays different angular distortions in the equatorial planes of the two Cu^II atoms; the chloride bridge is asymmetric, but the hydroxide bridge is symmetric. The chelate rings of the two Nca₂en ligands have different conformations, leading to a more marked bowing of one of the ligands compared with the other. This is the first reported dinuclear complex, and the first five‐coordinate complex, of the Nca₂en Schiff base ligand. Molecules of the dimer are associated in pairs by ring‐stacking interactions supported by C—H…Cl interactions with solvent molecules; a further ring‐stacking interaction exists between the two Schiff base ligands of each molecule.     

A Facile Synthesis of Oxoindenothiazine and Dioxospiro(indene‐2,4′‐thiazine) Derivatives from (Substituted ethylidene)hydrazinecarbothioamides

(E)‐2‐[2‐(1‐Substituted ethylidene)hydrazinyl]‐5‐oxo‐9b‐hydroxy‐5,9b‐dihydroindeno[1,2‐d][1,3]‐thiazine‐4‐carbonitriles and (E)‐5‐oxo‐[(E)‐(1‐substituted ethylidene)hydrazinyl]‐2,5‐dihydroindeno[1,2‐d][1,3]thiazine‐4‐carbonitriles have been obtained from the reaction of 2‐(substituted ethylidene)hydrazinecarbothioamides with 2‐(1,3‐dioxo‐2,3‐dihydro‐1H‐inden‐2‐ylidene)propanedinitrile ( 1 ) in ethyl acetate solution. However, (Z)‐6′‐amino‐1,3‐dioxo‐3′‐substituted‐2′‐[(E)‐(1‐phenylethylidene)hydrazono]‐1,2′,3,3′‐tetrahydrospiro(indene‐2,4′‐[1,3]thiazine)‐5′‐carbonitriles were observed during the reaction of N‐substituted‐2‐(1‐phenylethylidene)hydrazinecarbothioamides with ( 1 ). The structure assignment of products has been confirmed on the basis of ¹H‐, ¹³C‐NMR, and mass spectrometry, as well as theoretical calculations.     

Reduktion von 1,2-bis[(Z)-(2-nitrophenyl)-NNO-azoxy]benzol: Synthese von Cyclotrisazobenzol ( = (5E,6aZ,11E,12aZ,17E,18aZ)-5,6,11,12,17,18-Hexaazatribenzo[aei][1,3,5,7,9,11]cyclododeca-hexaen)

Reduction of 1,2-Bis[(Z)-(2-nitrophenyl)-NNO-azoxy]benzene¹: Synthesis of Cyclotrisazobenzene ( = (5E,6aZ,11E,12aZ,17E,18aZ)-5,6,11,12,17,18-Hexaazatribenzo[aei][1,3,5,7,9,11]cyclododeca-hexaene) Na₂S reduction of 1,2-bis[(Z)-(2-nitrophenyl)-NNO-azoxy]benzene ( 2 ) yielded 3 deoxygenated products: the (known) red 2,2′-((E,E)-1,2-phenylenbisazo)dianiline ( 3 , 23%), the orange 2-[2-((E)-2-aminophenylazo)phenyl]-2H-benzotriazol ( 4 , 55%) and the colorless 2,2′-(1,2-phenylene)di-2H-benzotriazol ( 5 , 13%). The constitutions of 3 – 5 and of 6 , the N-acetyl derivative of 4 , were deduced from their ¹H-NMR spectra (chemical shifts, couplings, and symmetry properties), and the configurations of 3 , 4 , and 6 at their N,N-double bonds are assumed to be the same as in 2 . Oxidation of 3 with 2 mol-equiv. of Pb(OAc)₄ afforded 5 (47%) and a novel, highly symmetrical macrocycle, called cyclotrisazobenzene ( 7 , 24%). The constitution of 7 as a tribenzo-hexaaza[12]annulene and its (E)-configuration at the N,N-bonds was confirmed by X-ray analysis. The molecular symmetry expressed by the ¹H-, ¹³C- and ¹⁵N-NMR spectra of 7 reveals a rapid torsional motion around the six N,C bonds. This implies that the N,N-double bonds in the cyclic 12π-electron system (or 24π-electron system if the benzene rings are included) of 7 are highly localized.     

Two‐Dimensional Acetylenic Scaffolding: Extended Donor‐Substituted Perethynylated Dehydroannulenes

Starting from (Z)‐bis(N,N‐diisopropylanilino)‐substituted tetraethynylethene (TEE), perethynylated octadehydro[12]‐ and dodecadehydro[18]annulenes were prepared by oxidative Hay coupling. The dodecadehydro[18]annulene with six peripheral N,N‐diisopropylanilino substituents was characterized by X‐ray crystallography. Elongation of the Z‐bisdeprotected TEE by Cadiot–Chodkiewicz coupling with 1‐bromo‐2‐(triisopropylsilyl)ethyne provided a Z‐configured bis(butadiyne), which after alkyne deprotection afforded under Hay coupling conditions N,N‐diisopropylanilino‐substituted perethynylated hexadecadehydro[20]‐ and tetracosadehydro[30]an‐nulenes. The diisopropylanilino substituents enhance the properties of these unprecedented all‐carbon perimeters in several distinct ways. They ensure their solubility, increase their stability, and importantly, engage in strong intramolecular charge‐transfer interactions with the electron‐accepting all‐carbon cores, resulting in intense, bathochromically shifted charge‐transfer bands in the UV/Vis spectra. The charge‐transfer character of these bands was confirmed by protonation‐neutralization experiments. The redox properties of the new carbon‐rich chromophores were investigated by cyclic voltammetry and rotating disk voltammetry, which indicated different redox behavior for aromatic (4n+2 π electrons) and antiaromatic (4n π electrons) dehydroannulenes.     

Bisresorcinol Derivatives from Grevillea glauca

Seven new and three known bisresorcinols, grevirobstol A (=5,5′‐((6Z,9Z)‐hexadeca‐6,9‐diene‐1,16‐diyl)bisresorcinol; 8 ), 5,5′‐[(8Z)‐hexadec‐8‐ene‐1,16‐diyl]bisresorcinol ( 9 ), and 2‐methyl‐5,5′‐[8Z)‐hexadec‐8‐ene‐1,16‐diyl]bisresorcinol ( 10 ) were isolated from the stems of Grevillea glauca. The new compounds were identified on the basis of spectroscopic data as (Z)‐6,7‐didehydroglaucone A ( 1 ), glaucones A and B ( 2 and 3 , resp.), 2‐(3‐hydroxyisopentyl)bisnorstriatol ( 4 ), 2‐(3‐methylbut‐2‐en‐1‐yl)bisnorstriatol ( 5 ), 2′‐methylgrebustol A ( 6 ), and glaucane ( 7 ).     

Linking Deltahedral Zintl Clusters with Conjugated Organic Building Blocks: Synthesis and Characterization of the Zintl Triad [R‐Ge9‐CHCHCHCH‐Ge9‐R]4−

The accessibility of triads with deltahedral Zintl clusters in analogy to fullerene–linker–fullerene triads is another example for the close relationship between fullerenes and Zintl clusters. The compound {[K(2.2.2‐crypt)]₄[RGe₉‐CH?CH? CH?CH‐Ge₉R]}(toluene)₂ (R=(2Z,4E)‐7‐amino‐5‐aza‐hepta‐2,4‐dien‐2‐yl), containing two deltahedral [Ge₉] clusters linked by a conjugated (1Z,3Z)‐buta‐1,3‐dien‐1,4‐diyl bridge, was synthesized through the reaction of 1,4‐bis(trimethylsilyl)butadiyne with K₄Ge₉ in ethylenediamine and crystallized after the addition of 2.2.2‐cryptand and toluene. The compound was characterized by single‐crystal structure analysis as well asNMR and IR spectroscopy.     

Isomerization of (all‐E)‐Cucurbitaxanthin A

Cucurbitaxanthin A (=(all‐E,3S,5R,6R,3′R)‐3,6‐epoxy‐5,6‐dihydro‐β,β‐carotene‐5,3′‐diol; 1 ) was submitted to thermal isomerization and to I₂‐catalysed photoisomerization. The structure of the main reaction products (9Z)‐ ( 2 ), (9′Z)‐ ( 3 ), (13Z)‐ ( 4 ), and (13′Z)‐cucurbitaxanthin A ( 5 ) was determined by their UV/VIS, CD, ¹H‐NMR, and mass spectra.     

A moderate distortion of the `picket‐fence' porphyrin (cryptand‐222)potassium chlorido[meso‐α,α,α,α‐tetrakis(o‐pivalamidophenyl)porphyrinato]ferrate(II) n‐hexane monosolvate

As representative porphyrin model compounds, the structures of `picket‐fence' porphyrins have been studied intensively. The title solvated complex salt {systematic name: (4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane)potassium(I) [5,10,15,20‐tetrakis(2‐tert‐butanamidophenyl)porphyrinato]iron(II) n‐hexane monosolvate}, [K(C₁₈H₃₆N₂O₆)][Fe(C₆₄H₆₄N₈O₄)Cl]·C₆H₁₄ or [K(222)][Fe(TpivPP)Cl]·C₆H₁₄ [222 is cryptand‐222 or 4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane, and TpivPP is meso‐α,α,α,α‐tetrakis(o‐pivalamidophenyl)porphyrinate(2−)], [K(222)][Fe(TpivPP)Cl]·C₆H₁₄, is a five‐coordinate high‐spin iron(II) picket‐fence porphyrin complex. It crystallizes with a potassium cation chelated inside a cryptand‐222 molecule; the average K—O and K—N distances are 2.81 (2) and 3.05 (2) Å, respectively. One of the protecting tert‐butyl pickets is disordered. The porphyrin plane presents a moderately ruffled distortion, as suggested by the atomic displacements. The axial chloride ligand is located inside the molecular cavity on the hindered porphyrin side and the Fe—Cl bond is tilted slightly off the normal to the porphyrin plane by 4.1°. The out‐of‐plane displacement of the metal centre relative to the 24‐atom mean plane (Δ₂₄) is 0.62 Å, indicating a noticeable doming of the porphyrin core.     

(E/Z)‐Isomerization of 3′‐Epilutein

3′‐Epilutein (=(all‐E,3R,3′S,6′R)‐4′,5′‐didehydro‐5′,6′‐dihydro‐β,β‐carotene‐3,3′‐diol; 1 ), isolated from the flowers of Caltha palustris, was submitted to both thermal isomerization and I₂‐catalyzed photoisomerization. The structures of the main products (9Z)‐ 1 , (9′Z)‐ 1 , (13Z)‐ 1 , (13′Z)‐ 1 , (15Z)‐ 1 , and (9Z,9′Z)‐ 1 were determined based on UV/VIS, CD, ¹H‐NMR, and MS data.     

Ferrocenophanes with Interannular Nitrogen–Gallium Bridges. 1,3,2‐Diazagalla‐[3]Ferrocenophanes and an 1‐Aza‐3‐Azonia‐2‐Gallata‐[3]Ferrocenophane. Synthesis and Structure

1,1′‐Bis(trimethylsilylamino)ferrocene reacts with trimethyl‐ and triethylgallium to give the μ‐[ferrocene‐1,1′‐diyl‐bis(trimethylsilylamido)]tetraalkyldigallanes. These were converted into the 1,3‐bis(trimethylsilyl)‐2‐alkyl‐2‐pyridine‐1,3,2‐diazagalla‐[3]ferrocenophanes, of which the ethyl derivative was characterized by X‐ray structural analysis. Treatment of gallium trichloride with N,N′‐dilithio‐1,1′‐bis(trimethylsilylamino)ferrocene affords μ‐[ferrocene‐1,1′‐diyl‐bis(trimethylsilylamido)]tetrachlorodigallane along with bis(trimethylsilyl)‐2,2‐dichloro‐1‐aza‐3‐azonia‐2‐gallata‐[3]ferrocenophane as a side product, and both were structurally characterized by X‐ray analysis. The solution‐state structures of the new gallium compounds and aspects of their molecular dynamics in solution were studied by NMR spectroscopy (¹H, ¹³C, ²⁹Si NMR).     

Chloro(η6‐p‐cymene)(phosphoramidite)ruthenium(II), a 16‐Electron Fragment Stabilized by an η2‐Aryl–Metal Interaction,and Its Use in Asymmetric Cyclopropanation

Chloride abstraction from the half‐sandwich complexes [RuCl₂(η⁶‐p‐cymene)(P*‐κP)] ( 2a : P* = (S_a,R,R)‐ 1a = (1S_a)‐[1,1′‐binaphthalene]‐2,2′‐diyl bis[(1R)‐1‐phenylethyl)]phosphoramidite; 2b : P* = (S_a,R,R)‐ 1b = (1S_a)‐[1,1′‐binaphthalene]‐2,2′‐diyl bis[(1R)‐(1‐(1‐naphthalen‐1‐yl)ethyl]phosphoramidite) with (Et₃O)[PF₆] or Tl[PF₆] gives the cationic, 18‐electron complexes dichloro(η⁶‐p‐cymene){(1S_a)‐[1,1′‐binaphthalene]‐2,2′‐diyl {(1R)‐1‐[(1,2‐η)‐phenyl]ethyl}[(1R)‐1‐phenylethyl]phosphoramidite‐κP}ruthenium(II) hexafluorophosphate ( 3a ) and [Ru(S)]‐dichloro(η⁶‐p‐cymene){(1S_a)‐[1,1′‐binaphthalene]‐2,2′‐diyl {(1R)‐1‐[(1,2‐η)‐naphthalen‐1‐yl]ethyl}[(1R)‐1‐(naphthalen‐1‐yl)ethyl]phosphoramidite‐κP)ruthenium(II) hexafluorophosphate ( 3b ), which feature the η²‐coordination of one aryl substituent of the phosphoramidite ligand, as indicated by ¹H‐, ¹³C‐, and ³¹P‐NMR spectroscopy and confirmed by an X‐ray study of 3b . Additionally, the dissociation of p‐cymene from 2a and 3a gives dichloro{(1S_a)‐[1,1′‐binaphthalene]‐2,2′‐diyl [(1R)‐(1‐(η⁶‐phenyl)ethyl][(1R)‐1‐phenylethyl]phosphoramidite‐κP)ruthenium(II) ( 4a ) and di‐μ‐chlorobis{(1S_a)‐[1,1′‐binaphthalene]‐2,2′‐diyl [(1R)‐1‐(η⁶‐phenyl)ethyl][(1R)‐1‐phenylethyl]phosphoramidite‐κP}diruthenium(II) bis(hexafluorophosphate) ( 5a ), respectively, in which one phenyl group of the N‐substituents is η⁶‐coordinated to the Ru‐center. Complexes 3a and 3b catalyze the asymmetric cyclopropanation of α‐methylstyrene with ethyl diazoacetate with up to 86 and 87% ee for the cis‐ and the trans‐isomers, respectively.